Field of the Invention
The present invention relates to an image forming apparatus and a sheet transfer apparatus connected to the image forming apparatus.
Description of the Related Art
Frames making up a housing of an image forming apparatus are formed of sheet metal in some cases. In such cases, some frames may be formed into a box-shaped frame, and overlapping portions of the box-shaped frame may be fixed with a screw or by welding so as to form the housing. In a technique disclosed in Japanese Patent Laid-Open No. 11-135956, a hole is provided in at least one of two overlapping sheet metal pieces, and the edge of the hole is welded to connect the two overlapping sheet metal pieces, and thus a box-shaped frame is formed.
However, in an image forming apparatus including a box-shaped frame having a corner fastened with a screw, loosening of the fastening connection may occur due to vibrations caused during transportation or by an accidental fall, for example. In addition, fixing of the frames by welding requires an additional equipment for welding.